Droppable wing-tip tank



April 25, 195i) V J CLARK E AL I 2,505,604

DROPPABLE WING TIP TANK Filed Feb. 1, 1947 5 Sheets-Sheet l INVENTORS JIR. Clark D.L. Mi: Farlcmd Fig. 5 BY )77 57W AT TOR N EY April 25, 119540 J. R. CLARK ET AL 2,595,6'M

DROPPABLE WING TIP TANK Filed Feb. 1, 1947 3 sheets sheet 2 ATTORNEY Aprifi 25, 1956 J R CLARK ET AL 2,5@5,6U4-

DROPPABLE WING TIP TANK Filed Feb. 1, 1947 3 Sheets-Sheet 3 L 170 i];- W HI I a I 4 INVENTORS J. R. Clark 6 D.L. Mc Farland ATTOR NEY Patented pr. 25, 1950 STATES PATENT OFFICE 2,505,604 DRIoPPABLEWING-TIP TANK John a. cle steam, and Donald. L. McFar land, Milford, Conn, assignors' to United Aircra'ftCorporation, East Hartford, Conn, a corporation of Delaware Application February 1, 1947,'Srial No. 725,902

7 Claims.

This invention relates to aircraft and" partic; ularly to aircraft having droppable fuel tanks or the like.

It is an object of this invention to provide a droppab le auxiliary fuel tank or other disposable unit, and particularly to provide improved disposable units of this type which are releasably attached to the wing tips of the aircraft.

Another object of the invention is to provide improved attaching and releasing mechanism for such a disposable unit.

A further object is the provision of means for separately controlling the mechanism for attaching each of a plurality of such units and for jointly controlling said mechanisms to effect the simultaneous release of all the units. l Another object of the invention is the provision of means for securing droppable fuel tanks rigidly yet releasably to the wing tips of an airplane.

A still further object of the invention is generally to improve the construction and operation of aircraft.

These and other objects and advantages of the invention will become apparent from the claims and from the following detailed description of the accompanying drawings which show a preferred embodiment of the invention.

In these drawings:

Fig. 1 is a perspective view of an airplane equipped with the improved droppable wingtip fuel tanks of this invention;

Fig. 2 is a similar view on a larger scale of one of the wing tips; s

Fig. 3 is a perspective view of thecooperating tank attaching and releasing mechanisms associated with the wing tip and tank structures;

Fig. 4 is a section taken on line 4-2 of Fig. 3.;

Fig. 5 is a section taken on line 55 of" Fig. 3 showing the mechanisms in the tank attached position;

Fig. 6 is a somewhat diagrammatic front View of one of the wingtips with a droppable fuel tank in position thereon;

Fig. 7 is a detailed perspective viewof the pilot operated controls for the tank attaching and releasing mechanisms; v I v Fig. 8 isa. section on line 88 of Fig.5; and

Pig. 9 is an enlarged View showing thecontrol cable connections to the drop tank release handles.

As herein shown, an airplaneigenerally lindi cated at HI has a fuselage l2 having the pilot compartment i l, empennage l6 and opppsitely extended wings I 8 and 20 on the tips22 of which 55 droppable fuel. tanks 26 are releasably and interchangeably supported. A v V The drop tank mounting and releasing mechanism of this invention is used to its fullest advantage on agwing tip ofthe type shown herein, but obviously can be used on wing tips of other designs. The wing tips 22 as herein shown are formed by revolving the upper camber line of a cross section of the wing takenat the tip of the drop tank to; be supported thereon.

January 31, 19/17, and assigned to the assignee' of this application. V H H The supporting and locking devices for the tanks 2 which areidenti-cal, eachincludes two cooperating-mechanisms, one of which is generallyindicatedby the numeral and is secured to the wing beam (not shown) .wholly withinthe shell of the wing tip. 22, and the other of which is indicated generally by the numeral 28 and is fastened in the well of the drop tank to suitableqribs not shown) therein. These mechanis'ms are" shown in Fig. 3 detached from their supportingstructure in the, relative positions which they assume just prior to securing a tank 24 to the Wing tip.

Mechanism 26 includes a casting 30 having lugs}? at its oppositemends through which suit,-

able fastenings are extended into thewing beam. to secure the mechanism rigidly and permanently,

inplace inthe wingtip. The casting 30 is formed with three pairs of outwardl extending website,

36 and 3%} which are joined by upper and lower.

stiffening flanges!!!) and 42 to provide an integral supporting structure for thelockingmechanism. The webs 34 and MLwhich extend above arcuate surfaces it and EQthatmerge into flanges 49 and 42 respectively.

The pads 44 and 35 upstand above said arcuate surfaces 43 and 59 an amount which equals the,

thicknessof theshell of the wing tips}; and these esia e h qu h upper nd, iewenre taheular openings SZ. and 5-4 ainthe .win tip shell, as is .1 shown most clearly inFig. 2. withithe shell. .sup-

ported on the arcuate surfaces 48 and 59 therewhi h e ap sed. a ent the ends of the casting are provided with upper. and lower arcuate faced rectangular pads Mend ceive one end of a latch operating link 66 which is pivoted to the latch on a pin 63. The other end of link 66 is pivoted on a pin III between a pair of arms I2 of a bushing M which is splined to an operating shaft I5 journaled in webs 34, 36 and 38. Shaft I5 is held against axial displacement in casting 38 by suitable nuts I6, one of which is shown in Fig. 3.

It will be evident that counterclockwise rotation of shaft I5, as viewed in Fig. 5, will break the toggle comprising arm 12 and link 66 which, in the latch projected position, is in fully straightened position. A stop is provided to engage the toggle joint and limit the clockwise rotation of bushing I4 and arms 12 beyond the toggle straightened position shown in Fig. 5, comprising a cap screw 18 threaded into a boss 68 and held in adjusted position by lock nuts 82.

Means controlled by the pilot is provided for rotating the shaft I5 in a counterclockwise direction, as VieWed in Fig. 5, to break the toggles for the two latches 56 and cause the latch faces thereof to be withdrawn beneath the arcuate surfaces of pads 44. To this end a cable sector pulley 84 is rotatably mounted on a bushing 86 which is splined to shaft I5. Cables 88 and 98 extend around opposite sides of the sector pulley and are secured thereto at 92 and 94 respectively. These cables pass between opposed guide pulleys 85 and 98 and over pulleys I88 and IIIZ, amidship of the airplane, and thence forward to a pilot's control lever I64 which is pivoted at I03 in a suitable support. Similar cables from the other wing of the airplane are connected to a parallel pilots control vere I88 and the two levers I84 and I88 terminate in aligned hand grips H8 and IIZ. The hand grips are provided with aligned grooves II4 (Fig. '7) adapted to receive a bar I I6 which is pivoted at one end on a pin I It in the grip I I2. Bar H6 is constantly biased by spring I20 into the grooves I I4 to lock the hand grips II 0 and I I2 together for joint operation. By swinging the bar II6 into the position shown in Fig. 7, however, either lever I84 or I88 can be operated separately.

At one side of pulley 84 and between this pulley and the adjacent web 35 is mounted a bifurcated arm I22 having its hub splined to shaft I5. Between the furcations of arm I22 two ears I25- and I26 are mounted on pivots I28 and I35 respectively. Ears I24 and I26 have parallel tails I32 and I34 provided with confronting spring locating pins for positioning the opposite ends of a compression spring I35 which constantly biases the parallel confronting faces I38 and I58 on the opposite ends of these ears into engagement with a pin I42 carried by pulley 84. The pin I52 operates in a notch in arm I22 between parallel opposed faces I44 and I 55 which are more Widely spaced than surfaces I58 and I48 on the ears I24 and I26, thus permitting the pin M2 to move the ears about their pivots a short distance before it engages and is stopped by one of the surfaces I44 or I46 of arm I22. Ears I24 and I26 are also provided with locking faces I48 and I50 respectively which cooperate in the normal position of the part shown in Fig. 4 with abutment faces I52 and I54 on a generally arcuate abutment member I 56 rigidly secured to one of the webs 36 by bolts I58. The locking faces I48, I55 and the abutment faces I52, I54 are arcuate, being struck about the pivots I28, I30 of ears I38, I48 in the position of the arm I22 shown in Fig. l. The ends of ears I24, I26, between the locking faces I58 and I55 thereof, are arcuate in configuration and conform to the arcuate inner face IEIl of abutment member I56. A similar arcuate surface I62 is provided on member I56 between abutmens I64 and I66, similar to abutments I52 and I56 above described and these abutments I64, I65 cooperate with surfaces I48 and I58 on ears I24, I25 to lock arm I22 in its other extreme position in which latches 55 are withdrawn beneath the surfaces of pads 44. It will be evident that when the locking faces I58, I56 are in engagement with either pair of abutments I52, I54 or I64, I53 the arm I22, shaft 15 and hence the toggle mechanism for operating latches 56 are all looked and remain locked until pulley 84 has been moved through a sufficient angular distance to cause pin to move one or the other of cars I58, I48 to release arm I22.

The pads 45 are provided with circular recesses I68 which are best shown in Fig. 5 for the reception of locking pins carried by mechanism 28 secured in the well of tank 24. Re-cesses I55 re ceive plugs I'Iil which are permanently staked into the casting 38 by pins H2. The plugs Ill? have hemispherical sockets I 54 therein which receive the rounded ends of generally cylindrical pins I16 carrier by mechanism 28. The plugs I16 are axially slidable in bushings H8 seemed in the casting I19 of mechanism 28 by radial stakes I88. Bushings I18 have axial screws I82 threaded therein for engaging the pins I 55 and adjusting them axially in bushings I78 so that the tank can be secured rigidly in place following installation on the wing tip. Casting I75 has a pair of arcuate surfaced pads I 85, which engage and conform to pads 45, through which pins I75 project and also has a similar pair of pads I86 which engage and conform to pads 44 on casting 38. The pads I have apertures I38 provided with bushings I88 fixed therein by radial stakes I82. Bushings I have recesses I93 containing plugs I94 having arcuate end faces I96 which conform to the end faces 58 of the latches 56. The plugs I94 are each fixed against rotation in bushings I98 by a stake I88. Axial adjusting screws 288 are threaded into bushings I95 and engage the plugs I94 and adjust them relative to the end faces 58 of latch plungers 51 in which position the screws 288 are held by lock nuts 28L When it is desired to attach drop tanks 24 to the wing tips 22, the control arms I84, I08 are moved to exert a pull on cables 88 to rotate pulleys 84 of each of the wing tip mechanisms 26 in a clockwise direction as viewed in Fig. 4. The pin H12 carried by pulley 84 will move ear I48 clockwise about its pivot I55 permitting the locking face I56 to pass over abutment face I54 as the pin I42 continues its clockwise movement. As soon as pin I 42 engages face I46 of arm I22 the shaft I5 will be rotated in a clockwise direction, as viewed in Fig. 4, or in a counterclockwise direction as viewed in Fig. 5, to break the toggle I2, 66 and withdraw the latches 56 beneath the surfaces of pads 44.

Considering Figs. 3 and 5, the method of attachment of a tank 24 to a wing tip 22 following the withdrawal of latches 56 will be evident. First pins HG are placed in bushings I18 of casting I19 and the rounded projecting ends of these pins are inserted in sockets I74 in plugs I10 of castings 3G. The rounded ends of these pins then act as pivot points about which the tank is swung inboard at the top until the apertures in bushings 598 are in register with apertures 62 in pads is. The left-hand control lever N14 is now freed from its connections with lever I08 by swinging the bar H6 out of the groove H4, and this lever 104 is swung upward to exert a pull on cable 50 which will move the arm I22 counterclockwise as viewed in Fig. 4 into the position shown in this figure in which the toggle i2, 66 is straightened and the latches 56 are projected into the recesses I93 in bushings I99 with the latch faces 59 thereof in engagement with the inner wall of the bushing 298, The adjusting screws 269 at the top of the tank are then screwed down to bring the plugs His into clamping engagement with the arcuate end faces 58 of latches 55, and the adjusting screws 582 are similarly axially adjusted to urge the pins I76 against the socketed plugs its to clamp the tank firmly in place on the wing tip structure. ccess to the adjusting screws I82 and 29B is obtained through the usual panels provided in the shell of the tank housing.

In accordance with this invention the tank supporting and releasing mechanism is constructed and arranged so that the tanks 24 on the left and right wing tips are interchangeable. To this end the latch plungers of latch members 56 are of circular cross section and are of the same size as the pins 115 and the recesses I18 and M3 in bushings H8 and I99 are identical. It will be evident from Fig. 3 that if the tank carried by casting I19 were to be placed on the wing tip of the opposite wing of the airplane, by bodily rotation of this tank over the top of the airplane the apertures #93 in bushings I90 would then receive the pins H3 and would become the lower pivot points previously described, while the bushings H8 would engage the latches 56.

When the pilot wants to release the tanks in flight he merely operates the twohand grips H and H2 to swing control levers I94, 108 downward and break the toggles i2, 66 which withdraws latches 55 from bushings I90 of both mechanisms 28. Although when the tanks are installed the plugs l 94 are adjusted by screws 200 to bear firmly against latches 55 supported by the locked toggles i2, 66, breaking of toggles 12, 66 withdraws the latches from abutting engagement with plugs led and also withdraws the latches from bushings 190. The tanks then swing outwardly and downwardly away from the wing tips without danger of interference with the latter. Since the hand grip I It), H2 are locked together by the bar I It the release of the two tanks will be simultaneous.

It will be evident that by this invention a simple and reliable drop tank supporting and releasing mechanism has been provided which not only greatly facilitates the attachment and the release of such tanks, but also enables the left and righthand wing tip tanks to be exchangeable.

It will further be evident that the releasing means provided insure safe disposal of a drop tank without danger of interference with the airplane and that accurately timed simultaneous disposal of the tank carried by the opposite wing is insured.

While only one embodiment of the invention has been shown and described herein, it will be evident that various changes may be made in the construction and arrangement of the parts without departing from the scope of the invention as defined in the following claims.

We claim:

1. An airplane having wings, disposable units adapted to be carried by the tips of said wings, each of said units having a well therein in which either of said wing tips is receivable, cooperating mechanisms carried by said wing tips and said units for releasably securing either of the latter on either of said wing tips, said wing tip carried mechanism having sockets below the median plane of said wing and latches projecting beyond the surface of said wing above the median plane thereof, said unit carried mechanism having lower apertures aligned with said sockets and upper apertures aligned with said latches, said latches receivable in either said upper or said lower apertures, pins insertable in either said upper or said lower apertures having projections receivable in said sockets, and pilot operated means operable while said projections are seated in said sockets for projecting and retracting said latches.

2. An airplane having wings, disposable units adapted to be carried by the tips of said wings said units having wells therein in which the wing tips are receivable, cooperating mechanisms carried by said wing tips and said units for releasably securing either unit on either of said wing tips in the same fore and :aft position relative to said wings, said wing tip carried mechanisms having sockets below the median planes of said wings and latches projecting beyond the upper surfaces of said wings, and said unit carried mechanisms including upper apertured members located in said wells in position to receive said latches and lower apertured members located in said wells in register with said sockets, pivot pins receivable in the apertures in said lower apertured members having their ends seated in said sockets, said pins also being receivable in the apertures in said upper apertured members and said latches being receivable in the apertures in said lower aperture members, whereby said units are interchangeable.

3. An airplane having a-wing, a disposable unit carried by the tip of said wing, said unit having a well therein adapted to enclose a portion of said wing tip, means for releasably connecting said unit to said wing tip including a recess in the surface of said well above the median plane of said wing, a latch member on said wing tip adapted to be projected into said recess, a toggle having one end connected to said latch and adapted when straightened to project said latch into said recess, pilot controlled mechanism for operating said toggle between its straightened and broken positions, said pilot controlled mechanism including a pilot actuated member, a member connected to said toggle and having a lost motion connection with said pilot actuated member, means carried by said toggle connected member for normally maintaining said toggle in its straightened position, and means carried by said pilot actuated member for releasing said toggle maintaining means to break said toggle and withdraw said latch member from its projected position.

4. An airplane having wings, disposable units carried by the tips of said wings having airfoil shapes including leading and trailing configurations, each of said units having a well therein adapted to receive a portion of a wing tip, means for mounting said units interchangeably on said wing tips including pairs of projections and mating recesses on the overlapping walls of said wing tips and wells both above and below the median planes of said wings, said projections and recesses being so constructed and arranged that any projection is receivable in any recess, whereby either unit can be mounted in the same fore and aft position on either wing tip of the airplane.

' 5. An airplane having a wing, a disposable unit carried by the tip of said wing having a well therein adapted. to enclose a portion of said wing tip, means for releasably connecting said unit to said wing tip including a latch carried by the latter above the median plane of said wing, pilot actuated means for operating said latch including a shaft journaled in said wing tip, an actuating member journaled on said shaft, a latch operating toggle including an arm on said shaft and a pivoted link connected to said arm and latch, a second arm secured to said shaft having opposed abutment surfaces therein, a projection on said actuating member located between said abutments providing a lost motion connection between said actuating member and said second arm, a pair of ears pivoted on said second arm having opposed abutment faces on opposite sides of said projection and between said abutment surfaces whereby said ears are engaged by said projection and rocked about their pivots prior to the engagement of said projection with said abutments, said ears having locking shoulders, fixed abutments cooperating with said shoulders, and means including a pilot operated member for moving said actuating member in opposite directions for unlocking said latch operating toggle and moving the latter between its straightened and broken positions to connect and release said unit.

6. An airplane having a wing, a disposable unit carried by the tip of said wing having a well therein adapted to enclose a portion of said wing tip, mechanism for releasably connecting said unit to said wing tip including a pivotal support between said wing tip and unit located below the median plane of said wing and a latch carried by said wing above said plane for engaging said unit, latch operating mechanism for projecting andretracting said latch, means for normally locking said latch operating mechanism, a pilot operated member for actuating said latch operating mechanism having a lost motion connection with said latch operating mechanism, and means operative as a result of the movement of said pilot operated member relative to said latch operating mechanism for unlocking said locking means.

7. An airplane having a wing, a disposable unit carried by the tip of said wing having a well therein adapted to enclose a portion .of said wing tip, mechanism for releasably connecting said unit to said wing tip including a pivotal support between said wing tip and unit located below the median plane of said wing and a releasable latch carried by said wing tip above said plane and cooperating with a latch engaging member carried by said unit, latch operating mechanism carried by said wing including a pivoted shaft and a member mounted on said shaft, a pilot operated actuating member, cooperating locking members, one pivotally mounted on said shaft mounted member and the other carried by fixed structure of said wing, means providing a lost motion connection between said shaft mounted member and said actuating member, and means operative upon movement of said actuating member by the pilot for moving said pivoted locking member to unlock said latch operating mechanism prior to engagement of said actuating member with said shaft mounted member.

JOHN R. CLARK. DONALD L. MCFARLAND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,584,358 Dement May 11, 1926 2,416,104 Lerche Feb. 18, 1947 2,421,699 Johnson June 3, 1947 FOREIGN PATENTS Number Country Date 292,513 Great Britain Dec. 13, 1928 

